Processing and Properties of 3-Layer Laminated Composites Based on Ultra High Carbon Steel and Mild Steel.

A combination of high temperature and low temperature hot rolling has successfully been used to prepare 3-layer laminated composite strips based on Ultra High Carbon Steel (UHCS) and Mild Steel (MS), having good interfacial bonding, no profuse carbon diffusion across the interface and fine spheroidized structure. No electron beam welding of the starting UHCS and MS plates at the edges was necessary. It has been shown that high temperature % elongation at fracture depends upon the volume fraction of UHCS in the composite strip. Despite a relatively high strain rate sensitivity valye, a 70% elongation has been observed for the 3-layer UHCS-MS composite strip having 0.7 volume fraction of UHCS at 670°C and 3×10-4 sec-1 strain rate. Although the UHCS layers exhibit superplastic behaviour at the chosen experimental conditions, the MS layer do not. This results in extensive damage in the MS layer leading to premature failure of the composite strip. It has been demonstrated that the high temperature % elongation at fracture can be improved upon by increasing the number of layers while keeping the volume fractions of UHCS and MS constant.